Report of Investigations 9161: Effect of Load Rate on Wood Crib Behavior

Details

• Journal Article:
  Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9161
• Personal Author:
  Barczak, Thomas M. ; Schwemmer, David E.
• Description:
  The effect of load rate on the load-carrying capabilities of wood cribs is investigated in this Bureau of Mines study. The modulus of deformation (stiffness) of wood crib blocks has been shown to increase with increases in rates of load application, causing larger load reactions for increases in convergence rates. Since wood cribs are tested in the laboratory at convergence rates that are orders of magnitude faster than typically would occur underground, wood cribs tested in the laboratory will react larger loads than the same cribs would react underground for the same displacement. Tests conducted in the Bureau's mine roof simulator on green wood crib blocks indicate that the increase in stiffness for increasing load rates diminishes at displacement rates beyond 0.1 In/min, making crib load nearly independent of load rate for rates faster than 0.1 In/min. Seasoned wood specimens were not as consistent in load-rate dependency. Some possible explanations of observed load-rate behavior on wood crib specimens are also postulated in this paper. [Description provided by NIOSH]
• Subjects:
  Coal Coal Mining Mining Occupational Health Safety Wood
• Keywords:
  Underground-supporting; Crib-walls; Wood; Coal-mining; Shoring; Loading-rate; Timbering-supporting; Mining-engineering; Stress-analysis; Cribs; Underground-mining; Loads-Forces
• Source:
  Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9161, 1988 Jan; :1-11
• Series:
  NIOSH Numbered Publications   ; Mining Publications  
• Subseries:
  Report of Investigations
• Document Type:
  Text
• Genre:
  Report
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PRC - Pittsburgh Research Center
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  16 pdf pages
• NIOSHTIC Number:
  nn:10005980
• NTIS Accession Number:
  PB88-230966
• Federal Fiscal Year:
  1988
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:6557d036feabc37c0502ac3af4bff1ffef70135e2fbafe6ab42fd926b5e62cce034833ec4ca0f7714dde4e93b21f20d8ec45299b367e5755501a63ea86206e3f
• Download URL:
  https://stacks.cdc.gov/view/cdc/10426/cdc_10426_DS1.pdf
• File Type:
  [PDF - 5.89 MB ]